Spirulina platensis Foliar Spraying Curcuma longa Has Improved Growth, Yield, and Curcuminoid Biosynthesis Gene Expression, as Well as Curcuminoid Accumulation

Round 1

Reviewer 1 Report

Dear Authors, thank you for the opportunity for contributing to your paper as a reviewer. I think, that the experimental design is appropriate, but the ms itself is a bit unbalanced to the direction of analytical side. The ms needs further clarifications as well.

General comments:

I have a general expression, that the main focus of the paper is on the analytical side. The extent of this part is much longer in the ms, which is obviously understandable as the methodology and the results should be explained and presented. However, the title of the ms does not fit to this alignment, so maybe a more precise title would be better. Additionally, the practical importance of the outcomes should be emphasized in a more elaborated way.

The materials and methods lack some important details about the spraying. Why did you choose these concentrations? What is the exact amount that a single plant got when sprayed? How did you separate the treatments when spraying was done? How many plants were planted into one plot?

I think, that in case of an eight months long vegetation period, the provided meteorological data is insufficient. At least as a supplementary material, please add a graph about it.

I don’t understand, why the tables are provided in the text and in the supplementary material as a duplicate. Please decide which to remove from the submission.

Why do you prefer to apply LSD as a statistical analysis? More reliable methods are widely available.

Detailed comments:

Table 9: I would suggest reducing the length of this table. molecular weight and formula are repeated in the case of every treatment. I suggest removing these two columns and the content could be moved to the supplementary. As the compounds detected are also overlapping, you could re-align the table and list all the compounds in the first column. The next columns could be all the four treatments. The crossing cells can contain the RT and the area, when relevant. If a compound was not detected in the case of a certain treatment, the cell should be left as blank. Please remove the brackets from the treatment names.

Figure 1 should be moved into the supplementary as it is very small in this form.

 

Author Response

Thank you for taking part of our Research article 

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors the design of the study is interesting. However, some shortcomings.

The quality of Figure 1 is poor and must be improved.

The methods are correctly presented. The materials have been adequately described. Each device used for characterization is presented in more detail.

The Conclusion must be revised. The main results must be presented in this section.

The paper is relatively easy to understand by readers from other areas.
The literature is sufficiently critical, current, and internationally evaluated. 

Author Response

Thank you for taking part of our Research article 

Author Response File: Author Response.docx

Reviewer 3 Report

The authors designed experiments regarding the effect of Spirulina platensis aqueous extract on vegetative development, bioactive components, and gene expression in Curcuma longa. The study would help understand the effectiveness of SAE as a biofertilizer. 

However, there are several areas that need to be addressed before publication. 

• Line 47-50, although proper citations are given, no detail of exact methods in this manuscript was included in the manuscript. 
• Explanation of unexpected performance of higher dosage group (3 g/L SAE) should be mentioned.
• The L.S.D. test of a, b, ab, bc, c is not properly explained in the table legend or supplementary. This should be addressed to ensure a better understanding from readers. 

Overall, this work is unique and has some significance in the research area. It should be considered for publication after addressing above mentioned issues. 

Author Response

Thank you for taking part of our Research article 

Author Response File: Author Response.docx

Reviewer 4 Report

Reviewer comments

Thank you for granting me the opportunity to review this interesting piece of work. In this study, Al Dayel and El Sherif investigated the effect of Spirulina platensis aqueous extract (SAE) foliar spray on the growth and yield of Curcuma longa as well as its ability to stimulate the synthesis of bioactive compounds. The upregulating ability of genes associated with the synthesis of curcuminoid following the application of SAE was additionally investigated. Kindly, find below my comments for your response.

Abstract

Line 9: The authors should revise “Spirulina platensis aqueous extract (SAE) foliar spraying…..” to “the application of Spirulina platensis aqueous extract in foliar spraying……………”

The authors should indicate what the “unique technique” is. This is important because there is no method stated in Abstract in its present form. Also, in the results, the authors report on results of gene sequencing but fail to mention it in the method of the Abstract.

Keywords: The authors should kindly delete “elicitation”, “effect ingredient”. They could add “foliar spraying” for example.

Introduction

Line 26: Kindly, replace “people” with “humans” and also replace “microalga” with “microalgae”

The authors should please consider introducing paragraphs in the sentences.

Materials and Methods

Line 46-47: The authors indicate that the “SAE was prepared according to (14).” For repeatability sake, it is necessary the authors describe the exact processes involved with the use of the method.

Line 49: The authors state this “Extraction and identification of vitamins and phytohormones of……” However, looking at the Table 1, there is the presence of “minerals” and results of some proximate analysis and vitamins that was carried out. The authors could consider revise that statement to “Nutritional and phytohormones characterisation S. platensis was carried out according to……” Also, the authors should please describe the methods used for the analysis of the “Proximate analysis”, “Mineral” and the “Vitamins”. It will be essential to expand the methods used.

Line 50: Again, the authors should expand the protocol “…..methods of (15, 16)” which was used

Line 64-65: The authors should revise this statement “The experiments were arranged in a completely randomized pattern that was repeated 20 times”. Could the authors clarify what they mean by the “experiment”? By “randomized” are the authors referring to the planting of the “experimental samples” and the “control?’’

Line 66-69: This statement “The experiments contained four treatment groups, namely, the control (distilled water) and three concentrations of SAE (1, 2 and 3 g/L), which were sprayed every two months throughout the vegetative growth stage”, is very confusing. They could consider “The study contained three experimental groups of Curcuma longa plants sprayed with aqueous extracts (1, 2 and 3 g/L) of SAE”.

Line 66: In Table 1, there is no varied concentration of SAE. The authors’ reference to it is not correct.

Line 74: Table 3. Tables must always stand alone. Thus, the authors should kindly expand the abbreviation “SAR”. Also, “ppm” should be expanded

Line 79-80: The authors should please describe extensively the method used for the chlorophyll and carotenoid measurements

Line 82: There is a challenge with the protocol used. Mineral analysis should always be preceded by the application of “Ash” matter

Line 88-89: The authors should expand on the method used for the determination of “Soil and water analyses”

Line 112: was the stock prepared from “the” three standards? What solvent type was used to prepare the stock solution?

Line 122: what is the known weight of the residue?

 

Statistical analysis

This statement “A completely randomized block design with 20 repetitions was used in the experiment”, should be under the Method section. Did the authors use both ANOVA and MANOVA? Which of the data was analysed using MANOVA? The authors should also indicate if they did check for data normality. Looking at Table 5 and 6 for example, they could analysis could have been analysed using ANOVA.

Results

Table 7: The authors did not state in the method how the carotenoids were analysed.

Line 208: The “Effect” is repeated

Figure 3: Figures must always stand alone. The authors should please consider expanding

Discussion

Line 286-287: The authors should provide a reference to support “Proteins, vitamins, vital amino acids and minerals are abundant in S. platensis powder (Table 3), and all these metabolites are required for plant growth and development”

The authors should introduce paragraphs in the discussion.

Conclusion

Line 323: The authors’ use of “correlated” may not be appropriate as no statistical “correlation” was done. They could probably use “corresponded” with.

 

Comments for author File: Comments.pdf

Author Response

Thank you for taking part of our Research article 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear authors,

Thank you for your corrections. however, there are several shortcomings:

- paragraph 95: spectrophotometer

-paragraph 251-253 empty spaces in the table

-paragraph 291 and 293 respectively CURS1 or CURS-1. In my opinion, there should be no more different notations.

paragraph 308 andall edit error

Author Response

Thank you for revising the paper 

Author Response File: Author Response.docx

Reviewer 4 Report

Reviewer comments

Thank you for revising the manuscript. The authors did not however address some of my previous comments. For example Lines 56-57.

Line 50-53: The authors should kindly revise the process. Do the authors’ use of “cells” mean the “powder?” The authors should expand “dist.” to “distilled”. What was the chilling conditions? The authors should state the temperature. This is important to ensure ease of adoption by other authors. The authors should revise this “The slurry was centrifuged at 5000 rpm for 10 minutes after being filtered.”

In this statement “The clear supernatant was collected and concentrated to 1000 ml”, what was the volume of supernatant that was concentrated to 1000 ml? The authors should thoroughly explain these for ease of repeatability and reproducibility by other potential authors who may want to cite the work.

Line 56-57: The authors should revise this “Extraction and identification of nutritional and phytohormones characterisation S. platensis was carried out according to the methods of (15,16).” The authors should explain what was extracted. The determination of mineral content (iron, phosphorus and manganese” does not involve “Extraction of bioactive compounds”. Also, the analyses of the “Proximate composition which includes moisture, fiber, fat, protein etc” does not involve “Extraction and identification”. In my first “Reviewer comments”, I suggested to the authors to “expand” the exact methods by “(15,16)” which was adopted by the authors. However, I realised that the authors have not done that in this revised version.

Page 8-10: There are blank pages that need to be revised. The manuscript needs a thorough formatting to address these challenges.

Author Response

Thank you for revising the paper 

Author Response File: Author Response.docx